| 摘要 |
PROBLEM TO BE SOLVED: To reduce the anti-aliasing noises by generating the digital voice signals of n-multiple sampling frequency via an over-sampling filter and then turning these voice signals into the ones of the original frequency through the nonlinear limiter processing. SOLUTION: The digital voice signals received from an input terminal 41 are supplied to an over-sampling filter 42, and the digital voice signals of n- multiple sampling frequency are generated and supplied to a digital nonlinear limiter 43. The limiter 43 performs the nonlinear limiter processing to reduce the anti-aliasing noises, and the voice signals are processed and supplied to a down-sampling filter 44. The filter 44 reduces the sampling frequency down to 1/n and turns the digital voice signals into the ones of the original frequency to output them to an output terminal 45. Then these voice signals are converted into the analog voice signals by a D/A converter. Thus, the anti-aliasing noises can be reduced by the filter 42 which supplies the digital signals and the limiter 43 which supplies the output of the filter 42. |
